The present invention relates to automatic equipment and, in particular, to web adjusting equipment whose performance is automatically controlled by initial manual adjustments.
In high volume industries such as the printing industry, high production rates, high efficiency and low waste are crucial. Thus it is important to operate the production machinery at its design limits. For machinery such as web handling equipment, the speed of operation is limited by the fact that an operator must make continual manual adjustments in the equipment. Incorrect or untimely adjustment of this running machinery often results in jamming and significant waste of material. To avoid such jamming, high speed machinery is often retarded to reduce in number the inevitable instances of error, whether it be due to inadvertance, poor judgment or poor eye to hand coordination.
It has been thought impossible to automate fully certain equipment where its adjustment relied upon visual observation by an operator. The visual phenonema being observed was deemed too subtle to regulate automatic adjusting apparatus. For example, in the printing industry a web is typically drawn from a roll and therefore has a tendency to remain curled as it is taken from the roll. This tendency to remain curled stems from web memory of the tensile and compressive stresses on opposing sides of the web. Were the web fed directly to a cutter, each severed piece of the web would be free to resume its prior curl. If it curls, the severed piece of web is likely to adhere within and jam the cutting die.
For this reason, it is known in the web handling art to initially induce a reverse curl as the web leaves its roll by conducting the web through a path having a radius of curvature which is smaller than and in an opposite direction to the curvature of the roll. However, since its diameter decreases as the roll expires, the tendency to curl correspondingly increases, requiring continual adjustment of the decurler to neutralize this curl. In the past this operation has been performed manually.
It is impractical to automate by measuring the diameter of an expiring roll since rolls are rapidly and automatically replaced in an apparatus that is densely packed with many moving parts. Furthermore, in some systems succeeding rolls may begin unrolling before its predecessor expires. Moreover, the pattern of adjustment is extremely varied and depends upon the nature and thickness of the web, the speed of operation, the length over which the printed pattern repeats, the separation between successive machines etc. Since the adjustment patterns have such variety it is impractical to simulate such patterns by known equipment.
For a spliced web the timing and extent of adjustment becomes severe, requiring a highly skilled operator. In this situation the tendency of the web to curl on either side of the splice is dramatically different. Consequently, the operator has been required to observe carefully the position of the splice so that the decurler is quickly and drastically readjusted just as the splice reaches the decurler. It will be appreciated that the operator must be very skilled to readjust the decurler such a large amount and retain accurate cancellation of curl.
While the printing arts were just discussed, the foregoing problem arises in other contexts where repetitive operations are performed on an indexed web or other work pieces.
Accordingly, there is a need for an apparatus which has flexibility to handle relatively complicated adjustments, but whose adjustment pattern can be quickly and easily changed by an unskilled operator. Preferably this operator can set the adjustment pattern by performing the actual adjustments on a real time basis and thereafter allowing an automatic apparatus to mimic him.